Influence of fixed charge concentration and water uptake on ion sorption in AMPS/PEGDA membranes

Ion sorption in highly charged, highly swollen membranes is influenced by fixed charge group concentration, as well as distribution of fixed charge groups.

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Continuum Modeling of Biological Tissue Growth by Cell Division, and Alteration of Intracellular Osmolytes and Extracellular Fixed Charge Density

Journal of Biomechanical Engineering ◽

10.1115/1.3192138 ◽

2009 ◽

Vol 131 (10) ◽

Cited By ~ 22

Author(s):

Gerard A. Ateshian ◽

Kevin D. Costa ◽

Evren U. Azeloglu ◽

Barclay Morrison ◽

Clark T. Hung

Keyword(s):

Cell Division ◽

Charge Density ◽

Water Uptake ◽

Biological Tissue ◽

Tissue Growth ◽

Fixed Charge ◽

Solid Matrix ◽

Continuum Modeling ◽

Fixed Charge Density ◽

Osmotic Effects

A framework is formulated within the theory of mixtures for continuum modeling of biological tissue growth that explicitly addresses cell division, using a homogenized representation of cells and their extracellular matrix (ECM). The model relies on the description of the cell as containing a solution of water and osmolytes, and having a porous solid matrix. The division of a cell into two nearly identical daughter cells is modeled as the doubling of the cell solid matrix and osmolyte content, producing an increase in water uptake via osmotic effects. This framework is also generalized to account for the growth of ECM-bound molecular species that impart a fixed charge density (FCD) to the tissue, such as proteoglycans. This FCD similarly induces osmotic effects, resulting in extracellular water uptake and osmotic pressurization of the ECM interstitial fluid, with concomitant swelling of its solid matrix. Applications of this growth model are illustrated in several examples.

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A Fixed Charge Model of the Transverse Tubular System of Frog Sartorius

The Journal of General Physiology ◽

10.1085/jgp.54.2.178 ◽

1969 ◽

Vol 54 (2) ◽

pp. 178-187 ◽

Cited By ~ 6

Author(s):

Stanley I. Rapoport

Keyword(s):

External Solution ◽

Fixed Charge ◽

Transverse Tubular System ◽

Charge Model ◽

Tubular System ◽

Charge Concentration ◽

Frog Sartorius ◽

System Volume ◽

Osmotic Pressure Difference ◽

T System

Volume changes of the transverse tubular system (T system) of frog sartorius in different solutions can be explained by a model which assumes fixed negative charges in the T system lumen, an open T system mouth, and a Donnan equilibrium between the T system and external solution. The T system volume is regulated by the osmotic pressure difference between the lumen and external solution, as well as by constraining forces whose nature is as yet unclear. The decreased swelling tendency produced by hypotonic solutions and increased tendency produced by some hypertonic solutions are ascribed to changes in the pressure constraint from the sarcoplasm. Fixed charge concentration was estimated tentatively from swelling and resistivity data to be between 0.1 and 0.4 M.

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